1. Field of the Invention
The present invention relates to a liquid discharge apparatus, a piezoelectric actuator, and a method for producing the liquid discharge apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2012-218314 discloses a liquid discharge apparatus formed by using a silicon single crystal substrate. The liquid discharge apparatus of Japanese Patent Application Laid-open No. 2012-218314 has a first substrate and a second substrate which are formed of silicon and a nozzle plate. The first substrate is formed with a liquid flow passage including a plurality of pressure chambers. A plurality of piezoelectric elements, which correspond to the plurality of pressure chambers, are provided on a vibration plate of the first substrate for covering the plurality of pressure chambers. The second substrate is joined to the vibration plate of the first substrate so that the plurality of piezoelectric elements are covered therewith. The nozzle plate is joined to the surface of the first substrate on the side opposite to the second substrate.
The liquid discharge apparatus of Japanese Patent Application Laid-open No. 2012-218314 is produced by performing the following steps (1) to (5).
(1) An oxidation treatment is applied to the surface of the first substrate of silicon to form the vibration plate of silicon oxide.
(2) Various type of film formation steps and patterning steps are repeatedly performed for the vibration plate to form piezoelectric elements and electrodes.
(3) The second substrate of silicon is joined to the vibration plate of the first substrate.
(4) The first substrate is polished and thinned until a predetermined thickness is obtained.
(5) Etching is performed from the surface of the first substrate on the side opposite to the vibration plate, and thus the liquid flow passage including the plurality of pressure chambers is formed for the first substrate.